## Abstract

: We present a numerical study of the asymmetric dumbbell model consisting of “molecules”

constructed as two different-sized Lennard-Jones spheres connected by a rigid bond. In terms of

the largest (A) particle radius, we report data for the structure and dynamics of the liquid phase for

the bond lengths 0.05, 0.1, 0.2, and 0.5, and analogous data for the plastic-crystal phase for the bond

lengths 0.05, 0.1, 0.2, and 0.3. Structure is probed by means of the AA, AB, and BB radial distribution

functions. Dynamics is probed via the A and B particle mean-square displacement as functions of

time and via the rotational time-autocorrelation function. Consistent with the systems’ strong virial

potential-energy correlations, the structure and dynamics are found to be isomorph invariant to a

good approximation in reduced units, while they generally vary considerably along isotherms of the

same (20%) density variation. Even the rotational time-autocorrelation function, which due to the

constant bond length is not predicted to be isomorph invariant, varies more along isotherms than

along isomorphs. Our findings provide the first validation of isomorph-theory predictions for plastic

crystals for which isomorph invariance, in fact, is found to apply better than in the liquid phase of

asymmetric-dumbbell models.

constructed as two different-sized Lennard-Jones spheres connected by a rigid bond. In terms of

the largest (A) particle radius, we report data for the structure and dynamics of the liquid phase for

the bond lengths 0.05, 0.1, 0.2, and 0.5, and analogous data for the plastic-crystal phase for the bond

lengths 0.05, 0.1, 0.2, and 0.3. Structure is probed by means of the AA, AB, and BB radial distribution

functions. Dynamics is probed via the A and B particle mean-square displacement as functions of

time and via the rotational time-autocorrelation function. Consistent with the systems’ strong virial

potential-energy correlations, the structure and dynamics are found to be isomorph invariant to a

good approximation in reduced units, while they generally vary considerably along isotherms of the

same (20%) density variation. Even the rotational time-autocorrelation function, which due to the

constant bond length is not predicted to be isomorph invariant, varies more along isotherms than

along isomorphs. Our findings provide the first validation of isomorph-theory predictions for plastic

crystals for which isomorph invariance, in fact, is found to apply better than in the liquid phase of

asymmetric-dumbbell models.

Originalsprog | Engelsk |
---|---|

Artikelnummer | 2010022 |

Tidsskrift | Liquids |

Vol/bind | 2 |

Udgave nummer | 4 |

Sider (fra-til) | 388-403 |

Antal sider | 16 |

ISSN | 2673-8015 |

DOI | |

Status | Udgivet - 9 nov. 2022 |

## Emneord

- asymmetric-dumbbell models
- plastic crystals
- isomorph theory
- hidden scale invariance